The present invention relates to a suspension subassembly for securement to a heavy vehicle trailer.
Heavy commercial vehicles typically employ trailing arm suspension systems, particularly in relation to axles of trailers of articulated vehicles or, potentially, rear axles of rigid body vehicles.
Heavy commercial vehicles (including trucks, buses and coaches) can be distinguished from light commercial vehicles (such as vans) and light passenger vehicles due to one or more of the following characteristics:
1. A laden weight in excess of approximately 3.5 tonnes.
2. The use of air actuated brakes as opposed to hydraulically actuated brakes (because air actuated brakes are better able to withstand the increased heat generated by the repeated braking of a vehicle having a weight in excess of approximately 3.5 tonnes).
Such vehicles (including trailers) also typically employ a pair of spaced parallel beams or rails that run a length of the vehicle and act as a front of a chassis upon which a vehicle body is mounted.
When used in heavy commercial vehicles, the trailing arms are typically pivotally mounted to chassis beams of the vehicle via a “hanger bracket” welded to the chassis beam and extending downwardly therefrom. The trailing arm extends rearwardly (i.e., towards a rear of the vehicle) to a mounting position for an axle and then further rearwardly to a mounting surface for an air spring. The air spring itself is mounted between the trailing arm and the chassis beam via an air spring pedestal.
Axles in such vehicles are typically substantially rigid beam-type axles (i.e., axles that extend between spindles upon which wheels at opposite sides of the vehicle are mounted). In some circumstances, the orientation of the trailing arms may be reversed to pivot at a rear of the trailing arm, in which case they are known as “leading arms.” For the purposes of this specification, the term trailing arm should also be understood to encompass leading arms.
Typically, the suspension manufacturer will supply a complete set of components to a trailer manufacturer including two trailing arms, an axle beam, two hanger brackets, two air springs, two dampers and two air spring pedestals for each axle installation. In some circumstances, the trailing arms may be secured to the axle before being supplied to the trailer manufacturer. In any event, the trailer manufacturer is required to assemble a number of components together. The assembly needs to be accurately completed to ensure that the wheels are accurately aligned to the trailer. This prevents undue stress from being placed on a suspension, the trailer and the wheel components.
It is known to use slider systems in which an entire running gear of the trailer is secured to a frame that may be released using retractable pins and slid along the chassis to rapidly vary a wheelbase to adjust load distribution and maneuverability characteristics of the trailer. In such systems, cross-members connect the hanger brackets on each side of the trailer, and the slider system and the frame is a complex multi-component assembly. An example of such a system can be seen in US 2005/0082814 (Ramsey).
The present invention seeks to overcome or at least mitigate the problems of the prior art.